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soumyaonweb
01-17-2009, 09:48 PM
I'm stuck with a problem regarding serial port communication using Hyper terminal. I'm using BAFO USB to serial converter.

My problem is that
When i'm shorting the Rx and Tx lines of the serial port, the characters are correctly echoed back to the Hyperterminal. But when i'm using the
MAX 232 chips the results are unpredictible. Sometimes it works fine but
sometimes the computer hangs. What may be the problem?

I have another query. After hanging when i restart the hyperterminal it
shows the last characters entered by me . IS there any buffer which
stores the characters?

debu
01-18-2009, 08:31 AM
@soumyaonweb: I trust that you have made the ground common? The ground of the Serial Port also must be connected to the ground of your circuit. I have faced a problem similar to yours, after making the aforementioned blunder.

Regards,

Debu :)

soumyaonweb
01-19-2009, 10:15 PM
Thanks for your reply....I have done that...but still the problem remains.

allbits
01-20-2009, 12:20 AM
which is your OS?

and did you mean,

> when you connect the RX and TX at the RS232 level you get the echo,

and when you connect the RX and TX at the TTL level after the MAX 232, you dont get it back??

1) check the ttl levels.
2) check the power.
3) check the ground line on the connector(pin 5)
4) check the RS232 level.

avinash_g
01-20-2009, 09:49 AM
I have also used the BAFO convertor. Even if you get every thing right then also during normal course of use it will irritate u with hangs.

The hang is such that even Shut down doesn't work. I think its driver is buggy. I strongly suggest u to first test it on a real COM port of a Desktop. Then move on to BAFO.

See my tutorial here at

http://extremeelectronics.co.in/avr-tutorials/rs232-communication-the-level-conversion/

:)

Hope it helps.